Displacement type pumps, compressors, engines and similar devices include tribological systems where rubbing and wear occurs. Sliding vanes on a cam surface, a piston reciprocating within a bore and bearings rotating in a journal are examples of such systems requiring a strong and durable wear surface. Existing technology makes use of replaceable or expendable liners that form the wear surfaces. Materials for such liners typically include nodular iron, bronze or stellite depending on the device and the media in contact with the liner. Liners with their supporting structure are designed to withstand system pressure, developed internal pressure and shock. It is also desirable that the rubbing or wear surfaces are constructed from durable materials to promote a long wearing life. Some examples of existing techniques for producing long wearing liner surfaces include plating, weld overlay, plasma flame spray and heat treatment. However, drawbacks associated with these existing practices include flaking, excessive wear, heat checking (i.e., cracking) and corrosion.
In an attempt to overcome some of these drawbacks, ceramic liners have been used. Ceramic materials are able to withstand high compressive stresses but are weak with respect to tensile strength that can result in a brittle form of failure. Therefore, if a ceramic is to be used as a liner, the liner and supporting structural design must have sufficient tensile strength capable of handling developed hoop stresses resulting from internal pressure.
In current ceramic liner structural design, a machined titanium ring is placed over a ceramic cam ring's outside diameter using a thermal difference fitting technique well known in the art. The technique places the ceramic cam ring liner in a pre-stressed compressive state while the outside titanium ring is placed in a pre-stressed tensile state. However, high machining costs are associated with this approach due to the precision fit that is required between the liner's outside diameter and the titanium ring's inside diameter.